1. Field of the Invention
This invention relates to a slide fastener, and more particularly to a fastener stringer having a continuous plastic filament spirally formed and woven into an edge of a stringer tape during the weaving thereof.
2. Prior Art
There have been proposed a number of slide fasteners or zippers of the type described, which comprise a woven stringer tape and a plastic filament woven into a longitudinal edge of the tape, the filament being usually formed into a helical coil structure consisting of a row of successive elongated loops or convolutions each having a coupling head, an upper leg and a lower leg and a connecting heel portion.
An advanced woven slide fastener of the type under contemplation was proposed in Japanese Patent Application No. 53-91 wherein a stuffing cord is inserted longitudinally through the coil of the filament and a guide cord or cords is disposed longitudinally of the filament in contact with the connecting heel portions of the coupling filament loops, the stuffing and guide cords being bound integrally with the coupling filament by the weave threads of the tape. While this earlier fastener product has advantages of its own, there is still much to be desired in respect of the positional stability of the fastener elements which would under the influence of external stresses become displaced longitudinally of the fastener. Furthermore, the warp threads covering the fastener elements would move out of place toward the connecting heel portions of the elements when the stringers are bent or twisted, with the results that the fastener elements are mismeshed or otherwise become inoperative.